Synthesis, Structure, and Magnetic Ordering of Layered (2-D) V-Based Tris(oxalato)metalates

• Published in: Inorganic chemistry 2005-11, Vol.44 (23), p.8433-8441
• Main Authors: Min, Kil Sik, Rhinegold, Arnold L, Miller, Joel S
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic051373+

The reaction of K3[MIII(ox)3]·3H2O [M = V (1), Cr; ox = oxalate], Mn(II)/V(II), and [N(n-Bu)4]Br in water leads to the isolation of 2-D V-based coordination polymers, {[N(n-Bu)4][MnIIVIII(ox)3]} n (2), {[N(n-Bu)4][VIICrIII(ox)3]} n (3), {[N(n-Bu)4][VIIVIII(ox)3]} n (4), and an intermediate in the formation of 4, {[N(n-Bu)4][VIIVIII(ox)3(H2O)2]} n ·2.5H2O (4a), while 1-D [VII(ox)(H2O)2] n (5) is obtained by using Na2ox and [V(OH2)6]SO4 in water. The structures of 1−5 have been investigated by single crystal and/or powder X-ray crystallography. In 1, VIII is coordinated with three oxalate dianions as an approximately D 3 symmetric, trigonally distorted octahedron. 1 is paramagnetic [μ eff = 2.68 μ B at 300 K, D = 3.84 cm-1 (D/k B = 5.53 K), θ = −1.11 K, and g = 1.895], indicating an S = 1 ground state. 2 exhibits intralayer ferromagnetic coupling below 20 K, but does not magnetically order above 2 K, and 3 shows a strong antiferromagnetic interaction between VII, S = 3/2 and CrIII, S = 3/2 ions (θ = −116 K) within the 2-D layers. 4 and 4a magnetically order as ferrimagnets at T c's, taken as the onset of magnetization, of 11 and 30 K, respectively. The 2 K remanent magnetizations are 2440 and 2230 emu·Oe mol-1 and the coercive fields are 1460 and 4060 Oe for 4 and 4a, respectively. Both 4 and 4a clearly show frequency dependence, indicative of spin-glass-like behavior. The glass transition temperatures were at 6.3 and 27 K, respectively, for 4 and 4a. 1-D 5 exhibits antiferromagnetic coupling of −4.94 cm-1 (H = −2J S i ·S i - 1 − gμB H·S i ) between the VII ions.